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alfik |
/*
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* Copyright (c) 2014, Aleksander Osman
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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module decode_ready(
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input enable,
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input is_prefix,
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input [3:0] decoder_count,
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input [95:0] decoder,
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input dec_operand_32bit,
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input dec_address_32bit,
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input dec_prefix_2byte,
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input [2:0] dec_modregrm_len,
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output dec_ready_one,
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output dec_ready_one_one,
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output dec_ready_one_two,
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output dec_ready_one_three,
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output dec_ready_2byte_one,
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output dec_ready_modregrm_one,
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output dec_ready_2byte_modregrm,
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output dec_ready_call_jmp_imm,
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output dec_ready_one_imm,
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output dec_ready_2byte_imm,
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output dec_ready_mem_offset,
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output dec_ready_modregrm_imm,
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output dec_ready_2byte_modregrm_imm,
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input consume_one,
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input consume_one_one,
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input consume_one_two,
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input consume_one_three,
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input consume_call_jmp_imm,
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input consume_modregrm_one,
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input consume_one_imm,
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input consume_modregrm_imm,
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input consume_mem_offset,
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output [3:0] consume_count_local,
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output dec_is_modregrm
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);
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//------------------------------------------------------------------------------
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wire [2:0] call_jmp_imm_len;
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wire [2:0] one_imm_len;
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wire [2:0] mem_offset_len;
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wire [2:0] modregrm_imm_only_len;
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wire [3:0] modregrm_imm_len;
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//------------------------------------------------------------------------------
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assign dec_is_modregrm = consume_modregrm_one || consume_modregrm_imm;
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//------------------------------------------------------------------------------
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/*
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* CALL imm:
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* (@decoder[7:0] == 8'h9A || @decoder[7:0] == 8'hE8)
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* decoder[7:0] == 8'h9A && operand_32bit --> 7
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* decoder[7:0] == 8'h9A --> 5
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* operand_32bit --> 5
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* --> 3
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*
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* JMP imm:
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* (@decoder[7:0] == 8'hEA || @decoder[7:0] == 8'hE9 || @decoder[7:0] == 8'hEB)
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* decoder[7:0] == 8'hEB --> 2
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* decoder[7:0] == 8'hEA && operand_32bit --> 7
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* decoder[7:0] == 8'hEA --> 5
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* operand_32bit --> 5
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* --> 3
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*/
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assign call_jmp_imm_len =
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// 8'hEB
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(decoder[1:0] == 2'b11)? 3'd2 :
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// (8'h9A or 8'hEA) and 32bit
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(decoder[1] == 1'b1 && dec_operand_32bit)? 3'd7 :
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// (8'hE8 or 8'hE9) and 16bit
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(decoder[1] == 1'b0 && ~(dec_operand_32bit))? 3'd3 :
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// else
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3'd5;
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/* Arithmetic:
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* @decoder[7:6] == 2'b00 && @decoder[2:1] == 2'b10
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* decoder[0] == 1'b0 --> 2
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* operand_32bit --> 5
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* --> 3
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*
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* PUSH imm:
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* (@decoder[7:0] == 8'h6A || @decoder[7:0] == 8'h68)
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* decoder[7:0] == 8'h6A --> 2
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* operand_32bit --> 5
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* --> 3
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*
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* TEST imm:
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* { @decoder[7:1], 1'b0 } == 8'hA8
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* decoder[0] == 1'b0 --> 2
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* operand_32bit --> 5
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* --> 3
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* MOV imm:
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* @decoder[7:4] == 4'hB
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* decoder[7:3] != 8'hB8 --> 2
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* operand_32bit --> 5
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* --> 3
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* Jcc:
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* @decoder_ready_2byte_imm && @decoder[7:4] == 4'h8
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* operand_32bit --> 5
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* --> 3
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*/
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assign one_imm_len =
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(~(dec_prefix_2byte) && ({ decoder[7:3], 3'b0 } == 8'hB0 || decoder[7:0] == 8'hA8 || decoder[7:0] == 8'h6A ||
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{ decoder[7:6], decoder[0] } == 3'b000 ))? 3'd2 :
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(dec_operand_32bit)? 3'd5 :
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3'd3;
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assign mem_offset_len = (dec_address_32bit)? 3'd5 : 3'd3;
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/* Arithmetic:
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* (@decoder[7:0] == 8'h80 || @decoder[7:0] == 8'h81 || @decoder[7:0] == 8'h83)
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* decoder[7:0] == 8'h80 || decoder[7:0] == 8'h83 --> 1
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* operand_32bit --> 4
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* --> 2
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*
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* IMUL:
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* (@decoder[7:0] == 8'h69 || @decoder[7:0] == 8'h6B)
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* decoder[7:0] == 8'h6B --> 1
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* operand_32bit --> 4
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* --> 2
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*
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* TEST:
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* { @decoder[7:1], 1'b0 } == 8'hF6 && { @decoder[13:12], 1'b0 } == 3'd0
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* decoder[7:0] == 8'hF6 --> 1
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* operand_32bit --> 4
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* --> 2
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*
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* MOV:
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* { @decoder[7:1], 1'b0 } == 8'hC6 && @decoder[13:11] == 3'd0
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* decoder[7:0] == 8'hC6 --> 1
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* operand_32bit --> 4
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* --> 2
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*
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* Shift:
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* { @decoder[7:1], 1'b0 } == 8'hC0 --> 1
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*
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*
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* prefix_2byte --> 1
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*/
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assign modregrm_imm_only_len =
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(dec_prefix_2byte || { decoder[7:1], 1'b0 } == 8'hC0 || decoder[1:0] == 2'b00 || decoder[1:0] == 2'b10 || decoder[2:0] == 3'b011)?
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3'd1 :
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(dec_operand_32bit)? 3'd4 :
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3'd2;
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assign modregrm_imm_len = { 1'b0, dec_modregrm_len } + { 1'b0, modregrm_imm_only_len };
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//------------------------------------------------------------------------------
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assign consume_count_local =
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(consume_one)? 4'd1 :
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(consume_one_one)? 4'd2 :
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(consume_one_two)? 4'd3 :
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(consume_one_three)? 4'd4 :
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(consume_call_jmp_imm)? { 1'b0, call_jmp_imm_len } :
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(consume_modregrm_one)? { 1'b0, dec_modregrm_len } :
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(consume_one_imm)? { 1'b0, one_imm_len } :
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(consume_modregrm_imm)? modregrm_imm_len :
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(consume_mem_offset)? { 1'b0, mem_offset_len } :
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4'd0;
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//------------------------------------------------------------------------------
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assign dec_ready_one = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= 4'd1;
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assign dec_ready_one_one = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= 4'd2;
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assign dec_ready_one_two = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= 4'd3;
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assign dec_ready_one_three = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= 4'd4;
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assign dec_ready_2byte_one = enable && dec_prefix_2byte && decoder_count >= 4'd1;
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assign dec_ready_modregrm_one = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= { 1'b0, dec_modregrm_len };
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assign dec_ready_2byte_modregrm = enable && dec_prefix_2byte && decoder_count >= { 1'b0, dec_modregrm_len };
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assign dec_ready_call_jmp_imm = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= { 1'b0, call_jmp_imm_len };
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assign dec_ready_one_imm = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= { 1'b0, one_imm_len };
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assign dec_ready_2byte_imm = enable && dec_prefix_2byte && decoder_count >= { 1'b0, one_imm_len };
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assign dec_ready_mem_offset = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= { 1'b0, mem_offset_len };
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assign dec_ready_modregrm_imm = enable && ~(is_prefix) && ~(dec_prefix_2byte) && decoder_count >= modregrm_imm_len;
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assign dec_ready_2byte_modregrm_imm = enable && dec_prefix_2byte && decoder_count >= modregrm_imm_len;
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//------------------------------------------------------------------------------
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//------------------------------------------------------------------------------
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// synthesis translate_off
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wire _unused_ok = &{ 1'b0, decoder[95:8], 1'b0 };
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// synthesis translate_on
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//------------------------------------------------------------------------------
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endmodule
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